Didn't get a chance to read all of the posts before, but I remember when jax could dodge tower shots....and twisted fate's ultimate was his e, worked globally, and had a global slow effect....scary times lol

wit's end used to steal mana
anivia's q could be cast into the corner of the map and hit everything globally
if maokai had GA and he died in the middle of his ultimate the game would completely drop
if skarner qss'd in the middle of his ult he could teleport him and his target anywhere, including spawn pool
akali's shadow dance used to be a skillshot
nasus's ult [on release] did 1% of the enemy's max hp per second per 1 ap, so with 100 ap you would deal 100% of their hp a second

and more.. but i cant think of any really

edit: you used to be able to dancewalk [walk while doing /dance command]